// Copyright (C) 2013 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.server.change;
import com.google.common.collect.LinkedListMultimap;
import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;
import com.google.gerrit.common.data.IncludedInDetail;
import org.eclipse.jgit.errors.IncorrectObjectTypeException;
import org.eclipse.jgit.errors.MissingObjectException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.Ref;
import org.eclipse.jgit.lib.RefDatabase;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevFlag;
import org.eclipse.jgit.revwalk.RevWalk;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Set;
/**
* Resolve in which tags and branches a commit is included.
*/
public class IncludedInResolver {
private static final Logger log = LoggerFactory
.getLogger(IncludedInResolver.class);
public static IncludedInDetail resolve(final Repository repo,
final RevWalk rw, final RevCommit commit) throws IOException {
return new IncludedInResolver(repo, rw, commit).resolve();
}
public static boolean includedInOne(final Repository repo, final RevWalk rw,
final RevCommit commit, final Collection<Ref> refs) throws IOException {
return new IncludedInResolver(repo, rw, commit).includedInOne(refs);
}
private final Repository repo;
private final RevWalk rw;
private final RevCommit target;
private final RevFlag containsTarget;
private Multimap<RevCommit, String> commitToRef;
private List<RevCommit> tipsByCommitTime;
private IncludedInResolver(final Repository repo, final RevWalk rw,
final RevCommit target) {
this.repo = repo;
this.rw = rw;
this.target = target;
this.containsTarget = rw.newFlag("CONTAINS_TARGET");
}
private IncludedInDetail resolve() throws IOException {
RefDatabase refDb = repo.getRefDatabase();
Collection<Ref> tags = refDb.getRefs(Constants.R_TAGS).values();
Collection<Ref> branches = refDb.getRefs(Constants.R_HEADS).values();
List<Ref> allTagsAndBranches = Lists.newArrayListWithCapacity(
tags.size() + branches.size());
allTagsAndBranches.addAll(tags);
allTagsAndBranches.addAll(branches);
parseCommits(allTagsAndBranches);
Set<String> allMatchingTagsAndBranches = includedIn(tipsByCommitTime, 0);
IncludedInDetail detail = new IncludedInDetail();
detail
.setBranches(getMatchingRefNames(allMatchingTagsAndBranches, branches));
detail.setTags(getMatchingRefNames(allMatchingTagsAndBranches, tags));
return detail;
}
private boolean includedInOne(final Collection<Ref> refs) throws IOException {
parseCommits(refs);
List<RevCommit> before = Lists.newLinkedList();
List<RevCommit> after = Lists.newLinkedList();
partition(before, after);
// It is highly likely that the target is reachable from the "after" set
// Within the "before" set we are trying to handle cases arising from clock skew
return !includedIn(after, 1).isEmpty() || !includedIn(before, 1).isEmpty();
}
/**
* Resolves which tip refs include the target commit.
*/
private Set<String> includedIn(final Collection<RevCommit> tips, int limit)
throws IOException, MissingObjectException, IncorrectObjectTypeException {
Set<String> result = Sets.newHashSet();
for (RevCommit tip : tips) {
boolean commitFound = false;
rw.resetRetain(RevFlag.UNINTERESTING, containsTarget);
rw.markStart(tip);
for (RevCommit commit : rw) {
if (commit.equals(target) || commit.has(containsTarget)) {
commitFound = true;
tip.add(containsTarget);
result.addAll(commitToRef.get(tip));
break;
}
}
if (!commitFound) {
rw.markUninteresting(tip);
} else if (0 < limit && limit < result.size()) {
break;
}
}
return result;
}
/**
* Partition the reference tips into two sets:
* <ul>
* <li> before = commits with time < target.getCommitTime()
* <li> after = commits with time >= target.getCommitTime()
* </ul>
*
* Each of the before/after lists is sorted by the the commit time.
*
* @param before
* @param after
*/
private void partition(final List<RevCommit> before,
final List<RevCommit> after) {
int insertionPoint = Collections.binarySearch(tipsByCommitTime, target,
new Comparator<RevCommit>() {
@Override
public int compare(RevCommit c1, RevCommit c2) {
return c1.getCommitTime() - c2.getCommitTime();
}
});
if (insertionPoint < 0) {
insertionPoint = - (insertionPoint + 1);
}
if (0 < insertionPoint) {
before.addAll(tipsByCommitTime.subList(0, insertionPoint));
}
if (insertionPoint < tipsByCommitTime.size()) {
after.addAll(tipsByCommitTime.subList(insertionPoint, tipsByCommitTime.size()));
}
}
/**
* Returns the short names of refs which are as well in the matchingRefs list
* as well as in the allRef list.
*/
private static List<String> getMatchingRefNames(Set<String> matchingRefs,
Collection<Ref> allRefs) {
List<String> refNames = Lists.newArrayListWithCapacity(matchingRefs.size());
for (Ref r : allRefs) {
if (matchingRefs.contains(r.getName())) {
refNames.add(Repository.shortenRefName(r.getName()));
}
}
return refNames;
}
/**
* Parse commit of ref and store the relation between ref and commit.
*/
private void parseCommits(final Collection<Ref> refs) throws IOException {
if (commitToRef != null) {
return;
}
commitToRef = LinkedListMultimap.create();
for (Ref ref : refs) {
final RevCommit commit;
try {
commit = rw.parseCommit(ref.getObjectId());
} catch (IncorrectObjectTypeException notCommit) {
// Its OK for a tag reference to point to a blob or a tree, this
// is common in the Linux kernel or git.git repository.
//
continue;
} catch (MissingObjectException notHere) {
// Log the problem with this branch, but keep processing.
//
log.warn("Reference " + ref.getName() + " in " + repo.getDirectory()
+ " points to dangling object " + ref.getObjectId());
continue;
}
commitToRef.put(commit, ref.getName());
}
tipsByCommitTime = Lists.newArrayList(commitToRef.keySet());
sortOlderFirst(tipsByCommitTime);
}
private void sortOlderFirst(final List<RevCommit> tips) {
Collections.sort(tips, new Comparator<RevCommit>() {
@Override
public int compare(RevCommit c1, RevCommit c2) {
return c1.getCommitTime() - c2.getCommitTime();
}
});
}
}